Xync is a mobile Lync Client for iOS devices (I think they also provide clients for other mobile platforms but as I only really care at this point about iOS I haven't done any research on those other platforms).
Xync so far is the only client I know of that does not need any additional infrastructure and supports all features of Lync (including conferencing, video, audio, screen sharing etc.). To setup the client is fairly easy – I used the automatic configuration method and was up and running after 2 minutes starting my first video conference from my iPhone.
From a functionality point of view this is an excellent app – everything I tried worked with the exception of a video conference between Xync and the Lync Mac client (I will try to figure this one out later).
But there are a couple of drawbacks:
The interface is clunky to say the least. No iPhone/iPad look and feel, weird design choices and sometimes intuitive but many times not intuitive enough (when I want to turn on the speaker during a call I just tap, get the a popup menu and can turn on the speaker – intuitive. When tapping on a person in my contact list I would expect the popup menu to start a call – not so, for this I have to click on the little arrow on the right side of the screen – not intuitive).
The pricing is done to maximize profit – therefore not user friendly. Whenever I have to pay for an iPhone AND an iPad app which do exactly the same I am just plain annoyed.
That said I am very satisfied with the app and can recommend it if you are looking for a quick way to give your iOS users access to Lync including all the features they would expect and it’s well worth the 20$ I paid for it (I just wish I didn’t have to pay this twice!).